This invention relates to a catheter, for example, a catheter to be inserted into a blood vessel such as a catheter for angiography or a catheter for dilating a blood vessel.
A catheter for angiography to be inserted into a blood vessel consisting of a main body formed of a somewhat soft thermoplastic resin and a rigidity imparting member consisting of a metallic braided wire (generally a stainless-steel wire) and disposed around the main body which is for inhibiting kinking or squash of the catheter while maintaining its high flexibility and for improving the torque transmission efficiency has conventionally been designed.
A catheter equipped with an inflatable member for dilating a stenosis portion in a blood vessel to improve the blood flow on the peripheral side of the stenosis portion which is for use in curing the stenosis portion is disclosed in EPA No. 349640 for example. This catheter comprises an inner tube made of a flexible synthetic resin, an outer tube made of a flexible synthetic resin and disposed coaxially with the inner tube and a foldable and inflatable member having a proximal end portion attached to the outer tube and a distal portion attached to the inner tube, and besides, the inner or outer tube is provided with a rigidity imparting member consisting of a metallic wire (e.g., a stainless-steel wire).
The rigidity imparting member used in the above catheter can inhibit its kinking or squash and improve its torque transmission efficiency to some extent. However, the catheter as a whole had low rigidity and particularly had a low efficiency of transmitting the pushing force given at its proximal end (pushability) and only an insufficient torque transmission efficiency.
Catheters are required to be introduced into peripheral blood vessels year by year, catheters which can be introduced into a more peripheral blood vessel has come to be desired.
However, the above catheter, whose body portion consists of a synthetic resin tube, needs to have a certain wall thickness and therefore necessarily has a large outer diameter. Accordingly, the blood vessel into which the catheter can be introduced is restricted by its outer diameter and the catheter could only be introduced into a blood vessel sufficiently larger than the outer diameter of the catheter.